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Figure 1
Design of the online microspectrophotometer. A new compact and portable microspectrophotometer was designed specifically as a module for the standard ESRF MX diffractometers. Two identical catadioptric objectives were mounted on a solid bracket that was in turn bolted to a high-precision XYZ translation stage (a). The mounting for the upper lens (light blue) has recessed micro-adjustment screws for aligning the two objectives to each other (focal cones depicted in light grey). Four locking nuts, one on each corner of the locking plate (dark blue), maintain this alignment. The rear of the translation stage (not visible) has a drilled recess to engage an alignment bar that is fixed permanently to the back plate of the diffractometer. This ensures correct and rigid docking, and the installation is completed by tightening two simple bolts. A CAD drawing of the instrument mounted on a MD2M diffractometer is shown in (b). The path of the X-ray beam is highlighted as red arrows and can be seen to intersect with the light path of the microspectrophotometer (yellow and green arrows). A typical installation is shown on ID14-2 (c). The objectives are mounted at 45° with respect to the φ axis to allow access for the cryostream, the X-ray fluorescence detector and the sample changer. A photograph of the device objective lens and accessories is shown in (d). A lens is shown complete with a rotating filter holder in place. The first mirror is visible on the front of the lens while the second larger mirror is situated internally at the rear of the lens. Fine threads have been machined onto the objective casing and allow positional adjustment and locking onto the mounting support (a). Filter holders can be inserted and removed while the instrument is installed on the beamline and offer the opportunity to adapt both the input and output transmission to match the experiment. The rotating filter holder offers the opportunity to insert polarizers into the light path. (e) Inset: a CAD drawing of a single objective design is shown. This set-up is essentially equivalent to the standard design except the second lower-objective has been replaced by a concave mirror. Both input and output transmission was achieved using a bifurcated fibre connected to the top lens. (e) Photograph: a prototype of this arrangement was constructed and successfully installed on ID14-2 ( f ). Inset: a dedicated fluorescence set-up was designed in order to optimize the collection of emission spectra while reducing contamination from the excitation source. ( f ) Photograph: a prototype was constructed and installed on ID14-4.

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ISSN: 1600-5775
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